Contaminated hypodermic needles present a hazard to health care personnel who may be inadvertently stuck by a needle in the course of or following routine medical procedures, such as blood drawings and injections. It has been reported that at least ten percent of health-care personnel are injured annually by needles and this estimate may be low based on a higher number of personnel who fail to report incidents of needle sticks. A number of infectious agents may be transmitted by contact with contaminated needles including non A-non B hepatitis, hepatitis B and human immunodeficiency virus (HIV). (Bonnett, J. Practical Nursing, pp. 33-35, June 1988). In particular, the transmission of fatal diseases such as Acquired Immune Deficiency Syndrome ("AIDS") to health care personnel has been demonstrated from accidental contact with contaminated needles, and poses a significant threat to such individuals.
Hypodermic needles are typically exposed for a certain period of time after use. During the time period in which the contaminated needle is exposed, individuals are susceptible to contact with and possible infection from the needle. Disposal of contaminated needles occurs by various procedures including recapping the needle and then disposing of the capped needle; cutting off the end of the needle, or disposal of the needle and syringe as a unit.
Various devices have been used in the past to cover hypodermic needles. These devices include those designed to hide the hypodermic syringe needle from view of the patient and/or to advance a needle into the patient's body or to administer preselected or multiple doses of medicament to the patient. For example, U.S. Pat. No. 2,876,770 describes a device for a hypodermic syringe for hiding the syringe needle from view of the patient. The device includes a sheath and a coil spring surrounding the hypodermic needle. The sheath is retracted as the needle is pushed into the patient's skin and since the sheath moves freely, the needle may be unintentionally exposed. U.S. Pat. No. 1,921,034 describes a carrying device for a syringe and employs a spring to advance the needle from the case a predetermined depth into the patient's skin. The device also contains a saturating material for sterilizing the needle before insertion into tissue. The sterilizing material seals the container after retraction of the needle. The syringe needle must be manually retracted into the case after use and may also be unintentionally exposed. U.S. Pat. No. 4,573,976 provides an injection apparatus having a needle guard which when extended obstructs access to the point of the needle and may be retracted to expose the needle. The extension and retraction of the needle is accomplished by interlocking units which are manually slid against one another to move a syringe carrying the needle. U.S. Pat. No. 4,664,653 describes a manually operated injection apparatus which is capable of administering repeated doses of a drug. U.S. Pat. No. 4,664,654 describes a hypodermic needle guard which includes a sliding member and a spring surrounding a needle. The sliding member may be retracted and locked into a retracted position to reveal the needle. The sliding member may be locked in position to expose the needle a certain amount and is unlocked by advancing the needle further into a patient. When the needle is withdrawn the guard may be locked into place to cover the needle; however, the guard may not be put into operation, such that the needle remains exposed. U.S Pat. No. 4,675,005 describes a retractable disposable syringe for manually retracting a needle into a syringe.
The aforementioned devices are intended for injection of medicaments into a subject. The devices may retain the needle in an exposed position during or after use allowing inadvertent puncture of the operator. There remains a need for a syringe device for injecting medicaments and/or withdrawing body fluids from a patient, and which eliminates exposure of an operator to a contaminated needle, to reduce the risk of contracting AIDS and other infectious diseases from inadvertent contact with the needle.